The above-referenced United States provisional application Ser. No. 60/173,427 is hereby incorporated herein by reference in its entirety.
N/A
Numerous types of hearing aids are known and are currently in use. Hearing aid users generally prefer hearing aid types that are minimally visible to third parties, but provide maximum performance in noisy environments. One common hearing aid type is worn behind-the-ear (BTE) and is quite visible to third parties. Such BTE hearing aids also generally do not perform well in noisy environments. For example, typical BTE hearing aids demonstrate Articulation-Index-weighted average Directivity Index (AIDI) values in the range of 2-3 dB (due to the high frequency shadowing of the Pinna, or earflap). For many users, BTE hearing aids simply do not provide the directivity performance sufficient to make the BTE viable in noisy environments.
In-the-ear (ITE) hearing aid solutions that are less visible and also provide improved performance in noisy environments have therefore been developed using directional microphone technology. One directional microphone for ITE applications is the D-MIC(copyright) of Etymoic Research, Inc. The D-MIC(copyright) directional microphone in an ITE hearing aid provides typical AIDI values in the range of 5+dB, a substantial improvement over BTE applications.
Despite the fact, however, that ITE hearing aids as such are less visible and provide substantial improvement in directivity performance, ITE hearing aids still require that the entire concha of the wearer""s ear be filled, and that the directional microphone be located on the near flat outer surface of the hearing aid. Such an arrangement is still quite visible.
Consequently, even less visible hearing aids have been developed for in the ear applications, namely in the canal (ITC) and completely in the canal (CIC) hearing aids. ITC and CIC hearing aids are discreetly located in the resonant portion of the ear canal, and thus do not require that the entire concha of the ear be filled. Hearing aid wearers, therefore, generally prefer the less visible ITC and CIC hearing aids over ITE hearing aids.
ITC and CIC hearing aids, however, do not perform as well as ITE hearing aids, or even BTE hearing aids, in noisy environments. Directional microphones simply do not provide useful directionality in ITC and CIC hearing aid applications because of the location of the hearing aid in the resonant portion of the wearer""s ear canal. The sound field at such a location has no detectable frequency dependent phase shift as is found in free space or on a surface in free space (as with an ITE hearing aid). Currently available ITC and CIC hearing aids therefore use only omni-directional microphones, and provide typical AIDI values in the range of xe2x88x920.5 to 0.2 dB. Such directionality performance is not adequate for most users in noisy environments.
It is thus an object of the invention to provide the improved directionality performance similar to ITE solutions for the less visible ITC and CIC hearing aids.
It is a further object of the invention to provide the improved directionality performance similar to ITE solutions for BTE hearing aids with little or no visual impact or prior art BTE hearing aid designs.
It is still a further object of the invention to provide an overall improved directivity performance for ITE hearing aid applications.
These and other objects of the invention are achieved in a microphone system having a hearing aid housing and a directional microphone mounted externally to the hearing aid housing. A link operatively couples the directional microphone to a component, such as, for example, a hearing aid amplifier or speaker, located internally to the hearing aid housing. The link may also be configured to mechanically mount the directional microphone to an external surface of the hearing aid housing, which surface may be, for example, a hearing aid faceplate.
In one embodiment, the link is a mounting arm that effectively mounts the directional microphone to a hearing aid faceplate and enables electrical connection of the directional microphone to the component within the hearing aid housing. For example, the mounting arm may be a rigid tube that mounts the directional microphone on one and is mounted to a faceplate on the other. Wires connecting the directional microphone to the internal component may therefore travel through the tube and faceplate.
The directional microphone may be configured externally to the hearing aid housing such that, when the hearing aid housing is inserted into the ear of a wearer, the microphone is located between the helix and tragus portions of the ear.
The directional microphone may comprise a directional microphone cartridge having a front inlet tube and a rear inlet tube both operatively coupled to the microphone cartridge. In one embodiment, the front tube is empty. In another embodiment, an acoustical impedance, such as, for example, a plurality of rods are placed longitudinally in the front inlet tube to improve the polar performance of the directional microphone. The rods may be, for example, monofilament fishing line.